This invention relates to outlets for use in fluidizing and discharging of fluidizable ladings from containers, including but not limited to transportation type containers, overland trucks and railway hopper cars, by pneumatic or gravity discharge.
Fluidizing outlets have heretofore been provided which have permeable filter members or membranes through which air under pressure may be passed to fluidize the lading and discharge the same from a railway hopper car or other hopper type containers.
Such permeable members or membranes are relatively expensive and are subject to being contaminated by either a dirty air supply system which clogs the permeable member during fluidization from the side opposite the lading, or by an improper outlet cleaning procedure. Such an improper cleaning procedure may occur, for example, when lading left in the outlet after unloading is attempted to be removed with a water wash only, without turning on the supply air. If the supply air is not turned on, the remaining lading often clogs the permeable membrane and it must be replaced to obtain efficient unloading rates. With contaminated supply air the permeable member must be cleaned and/or replaced frequently during unloading to maintain efficient unloading rates and prevent damage to the permeable member.
In the above mentioned parent application, a fluidizing outlet is disclosed in which plenum sheets define with the sides of the bottom pan of the outlet a plenum chamber and in which at least a portion of the lower edges of the plenum sheets are spaced from the sides of the bottom pan a distance to provide gaps which form first fluidizing openings. Furthermore, openings are also provided in the upper portion of the plenum sheets to provide second fluidizing openings to fluidize the lading. In accordance with this parent application the respective sizes of the first and second fluidizing openings are sufficiently large that the are not readily clogged by contaminates from dirty supply air or from improper outlet cleaning, but the openings are of sufficient size to fluidize the lading.
German Pat. No. 714,298 discloses upper and lower openings in plates (g) for fluidizing air used to pneumatically convey particulate material from said container (a) through a vertical conduit (b) which passes through conduit (a). However no specific size or location of openings is disclosed in the German Patent.
Further testing of the outlet of the present invention carried out since the filing of the above identified parent application has generated data which establishes that in order to obtain effective fluidization of the lading, to avoid clogging of the openings and to obtain substantially complete cleanout of the lading during unloading, that the first and second said fluidizing openings must have certain locations and be within certain size ranges.